Evaporator cover construction for an ice making apparatus

ABSTRACT

A cover or cap assembly for an evaporator of an ice making apparatus has an inner cover member forming a collection chamber receiving ice flakes or slush and being composed of an elastomeric material or similar thermally insulative material having a substantially low thermal conductivity relative to thermally conductive, metallic material and forming a surface having improved lubricity relative to the ice flakes or slush moving through the collection chamber. An outer, rigid backing member composed of a thermally conductive maetallic material receives the inner cover in nested assembly, and the inner cover has integrally formed insulative barriers between the backing member and the contiguously disposed portions of the ice making apparatus.

United States Patent Lyman [54] EVAPORATOR COVER CONSTRUCTION FOR AN ICEMAKING APPARATUS Inventor:

John B. Lyman, Bloomington, Minn.

Whirlpool Corporation, Benton Harbor, Mich.

May 22, 1970 Assignee:

Filed:

Appl. No.:

US. Cl ..62/354, 165/135 Int. Cl. ..Fc l/14 Field of Search ..l07/l4;62/354, 320, 74,

[56] References Cited UNITED STATES PATENTS 3,008,434 11/1961 Maldari107/14 2,428,995 10/1947 Rogers ..l00/l48 UX 3,196,624 7/1965 Reynolds..62/7l [4 1 Mar. 14, 1972 FOREIGN PATENTS OR APPLICATIONS 409,4995/1934 Great Britain ..62/354 Primary Examiner-William E. WaynerAttorney-James S. Nettleton, Thomas E. Turcotte, Burton H. Baker, DonaldW. Thomas, Gene A. Heth, Franklin C. Harter, Anthony Niewyk, Robert L.Judd and Hill, Sherman, Meroni, Gross & Simpson [5 7] ABSTRACT A coveror cap assembly for an evaporator of an ice making apparatus has aninner cover member forming a collection chamber receiving ice flakes orslush and being composed of an elastomeric material or similar thermallyinsulative material having a substantially low thermal conductivityrelative to thermally conductive, metallic material and forming asurface having improved lubricity relative to the ice flakes or slushmoving through the collection chamber. An outer, rigid backing membercomposed of a thermally conductive maetallic material receives the innercover in nested assembly, and the inner cover has integrally formedinsulative barriers between the backing member and the c ontiguouslydisposed portions of the ice making apparatus.

10 Claims, 5 Drawing Figures PATENTEUMAR 14 I972 3, 648,462

sum 2 OF 3 liY PATENTEDMAR 14 I972 SHEET 3 [IF 3 EVAPORA'FOR COVERCONSTRUCTION FOR AN ICE MAKING APPARATUS BACKGROUND OF THE INVENTION 1.Field of the Invention The present invention relates generally to icemakers and more particularly refers to a cover or cap assembly forming acollection chamber receiving ice flakes or slush harvested from arefrigerated surface.

2. Description of the Prior Art In one form of ice making apparatus,heretofore provided, ice products are produced by continuouslyharvesting and compressing ice flakes or slush which ice products wereformed on a refrigerated, cylindrical wall portion provided by anupright, tubular evaporator having an internal refrigerated bore surfacesized to cooperate with helical flights of a rotatable harvesting augerdisposed in closely spaced relationship thereto. A cover or cap extendsacross an upper end of the evaporator and forms a collection chamberreceiving the harvested ice flakes or slush and directing the same tosuitable compression means for compressing the ice flakes or slush intoa hard solidified product.

The ice flakes or slush may include ice particles, ice flakes and liquidwater, at a temperature of about 32 F., whereas the evaporator boresurface is maintained at a temperature lower than 32 F. so that a filmof ice forms thereon. The covers or caps generally utilized heretoforewere cooled by contact with refrigerated portions of the evaporator,thereby causing formation of an ice film on wall surfaces of thecollection chamber. Also, those covers were generally composed of amaterial which was wetted by water, thereby permitting the ice film toadhere to the collection chamber wall surfaces and buildup thereonthereby increasing the possibility of the collection chamber becomingclogged with an accumulation of ice and requiring shutdown periods forthawing out the apparatus.

SUMMARY OF THE INVENTION A cap or cover assembly, constructed inaccordance with the principles of the present invention, for forming acollection chamber on an ice making apparatus, includes an inner covermember having collection channels formed therein and being composed ofan elastomeric or similar thermally insulative material and an outer,rigid backing member receiving the inner cover in nested assembly andproviding the required structural strength for supporting superjacentlydisposed portions of the ice making apparatus.

The elastomeric or similar material has a thermal conductivitysubstantially lower than that of the outer backing member, which mayadvantageously be composed of a thermally conductive metallic material,such as sheet-form or cast stainless steel. While the metal backingmember may be cooled, due to its proximity to refrigerated portions ofthe evaporator, to a temperature below the freezing point of water,i.e., 32 F walls of the collection chamber formed by the inner cover aremaintained, due to its substantially lower thermal conductivity, at atemperature above the freezing point. Thus, ice will not be formed onthe walls of the collection chamber.

In order to implement flow of the ice flakes or slush through thecollection chamber, the inner cover is composed of a material having lowthermal conductivity which is not wetted by water and thus presents asubstantially frictionless or selflubricated surface on the collectionchamber walls.

The inner cover member has a configuration relative to the outer backingmember for forming integral portions interposed between the backingmember and refrigerated portions of the evaporator and between thebacking member and superjacently disposed nozzle means for compressingthe ice product into a hard form. Thus insulative barriers are formed atopposite ends of the backing member. A plurality of annular sealingridges abut an upper surface of a support flange on the evaporator forforming a labyrinth seal to prevent leakage of water between the coverassembly and the evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view withportions broken away to illustrate additional details of an ice makingapparatus having an evaporator cover assembly constructed in accordancewith the principles of the present invention;

FIG. 2 is an enlarged, partial sectional view, with parts omitted forclarity, of the ice making apparatus shown in FIG. l and illustrates thecover assembly of the present invention;

FIG. 3 is a bottom plan view of an inner cover member of a coverassembly of the present invention;

FIG. 4 is an enlarged, sectional view of a portion of the inner covermember of the present invention and illustrates an insulating flange andsealing ridges; and

FIG. 5 is a top plan view of the cover assembly of the present inventionwith portions broken away to illustrate additional details.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings,an ice maker of the present invention is shown generally at 10 andincludes an evaporator unit 11 having an internal bore forming acylindrical wall 12. An integrally formed evaporator passageway 13 has arefrigerant or coolant expanded thereinto by a refrigeration systemthrough an expansion valve or other pressure reducing means. Water isintroduced into the evaporator internally of the wall 12 through aninlet conduit 15 disposed near a base of the unit 11. The water tends tofreeze on the wall 12 in the form of a thin film of ice. One or morehelical flights 16 formed or carried on a rotating harvesting auger l7cooperate with the wall 12, which, in effect, forms a freezing surface14, whereby thin films of ice formed on. the freezing surface 14 will becontinuously harvested. The auger 17 progressively advances a mixture ofice particles, including slush and chunks upwardly in the unit 11towards a collection chamber I8 superjacent the evaporator unit 11.

Suitable fastening means, such as bolts 19, attach a radially outwardlyextending flange 21' formed on the evaporator unit 11 to a drive housing22. A shaft 23 is disposed centrally of the evaporator unit ll and has alower end portion supported within axially spaced bearing means in thedrive housing 22. Gear reduction means are driven by a prime mover suchas an electric motor M. The shaft 23 is dlisposed coaxially of theevaporator bore and has a driven connection with the gear reductionmeans. Water is prevented! from entering the drive housing 22 by sealmeans including a shaft seal 24 engaging the shaft 23.

The harvesting auger 17 includes a central hub portion 26 having athroughbore. A threaded portion 27 of the bore receives an upperthreaded end portion 28 of the shaft 23 to support the harvesting auger17 for corotation with the driven shaft 23. A cylindrical portion 29formed on the harvesting auger 17 and spaced concentrically inwardly ofthe refrigerated, freezing surface 14 has an outer diameter relativelylarger than a diameter of the shaft 23 and carries the helicallyextending flights or blades 16, which have edges 30 closely spacedadjacent the surface 14 to harvest the thin fllm of ice as theharvesting auger 17 rotates relative to the surface 14.

The collection chamber 18 is formed by a generally circular or invertedcupshaped cap means generally indicated at 3! and having a plurality ofchannels 32 receiving the ice flake product from the harvesting auger17. Each of the channels 32 extends in a generally spiral path ofincreasing cross-section for conducting the flake ice product dischargedfrom the evaporator unit II upwardly into a central passageway 33leading into an internal bore 34 of a compression and forming nozzle 35.The nozzle 35 has a generally outwardly extending flange 36 secured tothe cap means .31 by suitable fasteners, such as nut and bolt assembliesas at 37 and the cap means 31 are suitably secured by a plurality ofcircumferentially spaced bolts 38 to a radially outwardly extendingflange 39 on the evaporator unit. Thus, the drive housing 22, theevaporator 11, the cap means 31 and the compression nozzle 35 aredetachably secured in a stacked relationship by the fastening means 19,37 and 38.

In order to compress the flake ice product harvested from therefrigerated freezing surface 14 into a solid ice product, a compressionauger 41 mounted for corotation with the harvesting auger 17 receivesthe flake ice product from the collection chamber 18 and squeezes theice particles through the nozzle bore 34 to remove excess water and forman emergent solid column of ice at an upper end 42 of the nozzle 35. The

compression auger 41 has a depending, threaded stud 43 engaged into thethreaded bore 27 of the harvesting auger.

If desired, appropriately configured extrusion means may be attached toan outwardly extending flange 44 at the upper end 42 of the nozzle 35for forming the emerging, solid column of ice into a desiredconfiguration. The extrusion means may be designed to transversely shearthe emerging column of ice into ice cubes or otherwise shape the columninto desired configurations, for example, chipped ice, shaved ice,cracked ice or small ice cubes.

In accordance with the principles of the present invention, the capmeans or cover assembly 31 includes an inner cover member 51 having thecollection channels 32 and the central passageway 33 formed therein andan outer backing member 52 receiving the inner member in nested assemblytherewith. In order to retard the formation and accumulation of icewithin the collection channels 32, the inner cover 51 is composed of anelastomeric or similar plastic or rubber like material having asubstantially lower thermal conductivity than that of a metallicmaterial from which the outer backing S2 is constructed.

Thermal conductivity is defined as the quantity of heat usuallyexpressed in BTUs that flows in a unit of time through a unit area ofplate of unit thickness having a unit difference of temperature betweenits fuses. Metals usually have high thermal conductivity, steel forexample, have a K of 12-30 at a temperature range of 60 to 600 F.Insulator material such as rubber or plastic will be less than O.l at100 F. The plastic material used to make the inner cover member shouldpreferably have a thermal conductivity of less than 0.1 at 100 F.

The ice flakes or slush advanced by the harvesting auger into thechannels 32 includes ice particles, chunks, ice flakes and liquid wateris at a temperature of about 32 F whereas the refrigerated wall portions12 of the evaporator 11 disposed immediately subjacent of the cap means31 are maintained at a temperature below 32 F. to promote the formationof ice on the freezing surface 14. Due to the lower thermal conductivityof the inner cover 51, the collection chamber wall surfaces are notcooled below the freezing point of water, thereby retarding theformation and accumulation of ice on those wall surfaces.

The accumulation of ice within the collection channels 32 is furtherretarded by composing the inner cover 51 of a material which is notwetted by water so that ice particles and ice flakes will not adhere tothe collection channel wall surfaces. In such a manner, the inner cover51 forms the collection channel 32 with substantially frictionless orself-lubricating surfaces, thereby implementing the passage of the iceflakes or slush through the channels under the influence of a drivingforce created by rotation of the harvesting auger 17 and the compressionauger 41.

The outer backing member 52 is advantageously constructed of a rigidmetallic material having sufficient strength for supporting thesuperjacent nozzle means 35 and also having a higher thermalconductivity than that of the material of the inner cover 51.Advantageously, the outer backing member 52 may be constructed ofsheet-form stainless steel, which has the additional features ofcorrosion resistance.

As one example of the cap means 31 of the present invention, theformation and accumulation of ice within the collection channels 32 doesnot occur when the inner cover 51 includes a molded part composed of arubber and latex composition having a Durometer hardness in the order of80, and when the backing member 52 includes a part stamped or otherwiseformed of stainless steel. The thermal conductivity of the rubber andlatex composition, expressed in terms of the quantity of heat incalories which is transmitted per second through a plate 1 centimeterthick across an area of I square centimeter for a temperature differenceof 1 C., is approximately 0.0005. In comparison, the thermalconductivity of stainless steel is approximately 0.l l. A specificexample of the rubber and latex composition is sold by AKU-Goodrich,Holland, under the trade name No. 1072 l-Iycar. That material is anodorless, tasteless material approved by the Food and DrugAdministration for use with potable water.

As illustrated in the drawings, the inner cover 51 has a circular,inverted, cup-shaped central body portion 53 sized to extend across andcover the evaporator bore formed by the cylindrical wall 12. The bodyportion 53 has an outer boundary including a planar top wall 54 and asubstantially cylindrical sidewall 56 joined to the top wall by anarcuately chamfered comer edge 57.

Each of the collection channels 32, formed in the inner cover body 53,has a pair of equally spaced sidewalls 58, 58 and a bight portion 59joining the sidewalls and arranged relative thereto for forming thechannels 32 with a U-shaped cross section. The equally spaced sidewalls58, 58 extend from a periphery 61 of the inner cover body portion 53 ina generally spiral path and open laterally into the central passage 33formed centrally of the body portion. The spirally extending channels 32collect the ice flakes or slush advanced by the harvesting auger l7 anddirect the ice product upwardly through the central passage 33 and intothe nozzle bore 34. The bight portion 59 is axially outwardly inclinedin a manner to form the collection channels 32 with a cross sectionprogressively increasing in area in the direction of ice productmovement.

An annular, central web portion 63 of the backing member 52 received theinner cover body portion 53 in nested relationship and is characterizedby a generally arcuately shaped transverse cross section formedcomplementally to the arcuate chamfered edge 57. A top wall 64, axiallyoffset from the central web 63 extends parallel to the cover top wallportion 54 and has a lower surface 66 spaced from the cover top wall toform an annular space 67 therebetween. A plurality of circumferentiallyspaced apertures 68 extend through the top wall 64 of the backing memberand intersect the annular space 67, thereby forming a plurality of boltholes for receiving an equal number of the nut and bolt assemblies 37.Each of the nut and bolt assemblies 37 has a bolt 69 including a bolthead 71 disposed in the annular space 67 and welded or otherwiseretained against rotation in a manner to facilitate assembly of thenoule means 35 with the cap means 31.

In order to close an inwardly opening end of the space 67 and toinsulate the backing member top wall 64 from the ice product driventhrough the central passage 33, the inner cover 51 has an upstanding,hollow neck 72 extending upwardly beyond terminal ends 73 of the backingmember top wall 64. The terminal ends 73 are arranged to form anaperture closely receiving the cover neck 72.

An out-turned flange 74 extending outwardly of an upper end of the neck72 forms a laterally opening channel 75 receiving the terminal ends 74and overlaps the backing member top wall 64, thereby forming aninsulative barrier integral with the inner cover for isolating themargin portion from the ice and for insulating the margin portions fromthe superjacent nozzle 35. A recess 77 in the nozzle 35 receives theout-turned flange 74, and, if desired, a liner 78 formed in the nozzlethroughbore 34 may have a foot portion 79 abutting the out-turned flangein sealing engagement therewith.

The cover neck 72 has internal walls 81 forming an upward extension ofthe central passage 33 to innerconnect the nozzle throughbore 34 withthe central passage 33. In order to retard rotation of the ice productas the compression auger 41 rotates, the nozzle bore 34 may have anoncircular configuration in transverse cross section, the centralpassage 33 may have a configuration complemental to the nozzle boreconfiguration. As illustrated in the drawings, the transverse crosssectional configuration of the nozzle bore 34, and thus the centralpassage 33, may be in the form of a square.

It is also contemplated by the present invention to configure the innercover 51 with an integral portion interposed between the radiallyoutwardly extending support flange 39 and the evaporator unit 11 and theouter backing member 52, thereby forming an insulative barrier. Thus,the inner cover 511 has a radially outwardly extending base flange 82formed around the periphery 61 of the central body portion 53. Anunderneath surface 83 of the base flange 82 overlaps and abuts an uppersurface 84 of the evaporator flange 39. An annular attachment flange 86on the outer backing member 52 extends radially outwardly of the centralweb 63 and overlaps the base flange 82. Thus, the attachment flange 36,the base flange 82 and the support flange 39 are stacked in laminaradjacency with the cover base flange forming an insulative barrierbetween the other two flanges.

A plurality of circumferentially spaced clearance apertures 87 areformed in the attachment flange 86 in registry with an equal number oftapped holes 88 in the evaporator flange 39 and with an equal number ofnotches 91 extending inwardly of a periphery 92 of the cover flange 83.The attachment bolts 38 pass through the clearance apertures 97 and thenotches 98 and threadingly engage into the tapped holes 89, therebydetachably clamping the backing member 52, the inner cover 51 and theevaporator 11 in firm assembly. A depending, peripheral lip 93 formed onthe outer backing member 52 pilots on an outer cylindrical end 94 of theevaporator support flange 39 to center the cap means 31 on theevaporator llll.

Sealing means for preventing the leakage of water outwardly between thecap means 31 and the evaporator 11 include a plurality of concentric,radially spaced, circular sealing ridges 96 integrally formed on theinner cover 51, as illustrated in detail in FIG. 4. The sealing ridges96 depend from the underneath surface 83 of the inner cover base flange82 and have a V-shaped configuration in transverse cross section. Whenthe cap means 31 are clamped in firm assembly with the evaporator ill,the sealing ridges 96 abut the upper surface 84 of the evaporator flange39 and are slightly compressed in a manner to form a labyrinth sealbetween the cover base flange and the evaporator flange.

Although those versed in the art may suggest various minormodifications, it should be understood that I wish to incorporate withinthe scope of the patent warranted hereon all such modifications asreasonably and properly come within the scope of my contribution to theart.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

ll. In an ice maker, means forming an evaporator unit having aninternal, refrigerated cylindrical surface forming an internal bore;

auger means rotatable within said evaporator bore and hav ing flights inclose proximity to said refrigerated surface for harvesting and axiallyupwardly advancing an ice flake product frozen on said surface;

collection means receiving the ice product harvested by said auger, saidcollection means comprising an inner cover member having a centralpassageway and a central, circular, inverted cup-shaped body portionsized to extend across and close an upper end of said evaporator bore,said body portion forming a collection chamber receiving the ice flakeproduct upwardly advanced by said-auger means, and directing andmechanically transferring the ice flake product to said passageway; and

an outer backing member having said cover nested therein and clampingsaid cover to subjacent portions of an ice maker,

said cover being composed of a thermally insulative material having alower thermal conductivity than that of material forming said outerbacking member,

whereby the mechanical transfer of ice through said collection chamberis enhanced.

2. In an ice maker as defined in claim 1 and further characterized bysaid cover material being an elastomeric material forming a non-wettablesurface, thereby retarding adhesion of the ice flake product to surfacesof said cover.

3. In an ice maker as defined in claim 2 and further characterized by:

said cover being composed of a rubber and latex composition; and

said outer backing member being constructed of sheet-form stainlesssteel.

4. In an ice maker as defined in claim 1 and further characterized bymeans integral with said cover and forming insulative barriers betweensaid backing member and portions of an ice maker disposed contiguouslyof said cover.

5. In an ice maker,

means forming an evaporator unit having an internal,

refrigerated cylindrical surface forming an internal bore;

an inner cover member having a central passageway and a collectionchamber receiving ice flake product and directing the same to saidpassageway; and

said cover having a central, circular, inverted cup-shaped body portionsized to extend across and close said evaporator bore;

said cover body portion having a plurality of collection channels formedtherein and extending from a periphery thereof and to said centralpassage in a generally spiral path; and

an outer backing member having said cover nested therein and clampingsaid cover to subjacent portions of an ice maker,

said cover being composed of a thermally insulative material having alower thermal conductivity than that of material forming said outerbacking member.

6. In an ice maker,

means forming an evaporator unit having an internal,

refrigerated cylindrical surface forming an internal bore; saidevaporator having a radially outwardly extending support flange formedat an upper end portion;

an inner cover member having a central passageway and a collectionchamber receiving ice flake product and directing the same to saidpassageway; and

an outer backing member having said cover nested therein and clampingsaid cover to subjacent portions of an ice maker,

said cover being composed of a thermally insulative material having alower thermal conductivity than that of material forming said outerbacking member;

said backing member having an annular attachment flange sizedcomplementally to said support flange;

said cover having a radially outwardly extending base flange formedintegral therewith and interposed between said support flange and saidattachment flange in laminar adjacency thereto; and

attachment means securing said attachment flange to said support flangefor clamping said backing member, said cover and said evaporator in firmassembly, whereby said cover base flange forms an insulative barrierbetween refrigerated portions of said evaporator and said backingmember.

7. In an ice maker as defined in claim 6 and further characterized by aplurality of concentric, radially spaced, depending sealing ridgesformed integrally on said cover base flange and sealingly abutting anupwardly projecting surface of said support flange for forming alabyrinth seal between said cover and said evaporator.

8. In an ice maker,

means forming an evaporator unit having an internal,

refrigerated cylindrical surface forming an internal bore;

an inner cover member having a central passageway and a collectionchamber receiving ice flake product and directing the same to saidpassageway; and

said cover having a central, circular, inverted cup-shaped body portionsized to extend across and close said evaporator bore; said cover havingan upstanding neck formed integral with said body portion and having anout-turned flange forming a laterally opening channel; an outer backingmember having said cover nested therein and clamping said cover tosubjacent portions of an ice maker, said cover being composed of athermally insulative material having a lower thermal conductivity thanthat of material forming said outer backing member; said backing memberhaving an annular top wall overlying said cover body portion and havinginner terminal ends received in said laterally opening channel andforming an aperture closely receiving said upstanding neck. 9. In an icemaker, means forming an evaporator unit having an internal refrigeratedcylindrical surface forming an internal bore; ice collection meanscomprising a cover member composed of a thermally insulative materialand having a central passageway and a collection chamber receiving anice flake product from said evaporator and directing the product to saidcentral passageway;

said cover having a central body portion sized and configured to extendacross and close and end of said evaporator bore; said cover bodyportion having a plurality of collection channels therein forming saidcollection chamber and extending from a periphery of said body portionand to said central passageway in a generally spiral path formechanically transferring the ice flake product received from theevaporator to said central passageway, with the thermally insulativematerial on the wall surfaces of said collection channels acting toenhance the mechanical transfer of ice product to said centralpassageway. 10. In an ice maker as defined in claim 9 and furthercharacterized by:

attachment means securing said base flange to said support flange.

1. In an ice maker, means forming an evaporator unit having an internal,refrigerated cylindrical surface forming an internal bore; auger meansrotatable within said evaporator bore and having flights in closeproximity to said refrigerated surface for harvesting and axiallyupwardly advancing an ice flake product frozen on said surface;collection means receiving the ice product harvested by said auger, saidcollection means comprising an inner cover member having a centralpassageway and a central, circular, inverted cup-shaped body portionsized to extend across and close an upper end of said evaporator bore,said body portion forming a collection chamber receiving the ice flakeproduct upwardly advanced by said auger means, and directing andmechanically transferring the ice flake product to said passageway; andan outer backing member having said cover nested therein and clampingsaid cover to subjacent portions of an ice maker, said cover beingcomposed of a thermally insulative material having a lower thermalconductivity than that of material forming said outer backing member,whereby the mechanical transfer of ice through said collection chamberis enhanced.
 2. In an ice maker as defined in claim 1 and furthercharacterized by said cover material being an elastomeric materialforming a non-wettable surface, thereby retarding adhesion of the iceflake product to surfaces of said cover.
 3. In an ice maker as definedin claim 2 and further characterized by: said cover being composed of arubber and latex composition; and said outer backing member beingconstructed of sheet-form stainless steel.
 4. In an ice maker as definedin claim 1 and further characterized by means integral with said coverand forming insulative barriers between said backing member and portionsof an ice maker disposed contiguously of said cover.
 5. In an ice maker,means forming an evaporator unit having an internal, refrigeratedcylindrical surface forming an internal bore; an inner cover memberhaving a central passageway and a collection chamber receiving ice flakeproduct and directing the same to said passageway; and said cover havinga central, circular, inverted cup-shaped body portion sized to extendacross and close said evaporator bore; said cover body portion having aplurality of collection channels formed therein and extending from aperiphery thereof and to said central passage in a generally spiralpath; and an outer backing member having said cover nested therein andclamping said cover to subjacent portions of an ice maker, said coverbeing composed of a thermally insulative material having a lower thermalconductivity than that of material forming said outer backing member. 6.In an ice maker, means forming an evaporator unit having an internal,refrigerated cylindrical surface forming an internal bore; saidevaporator having a radially outwardly exteNding support flange formedat an upper end portion; an inner cover member having a centralpassageway and a collection chamber receiving ice flake product anddirecting the same to said passageway; and an outer backing memberhaving said cover nested therein and clamping said cover to subjacentportions of an ice maker, said cover being composed of a thermallyinsulative material having a lower thermal conductivity than that ofmaterial forming said outer backing member; said backing member havingan annular attachment flange sized complementally to said supportflange; said cover having a radially outwardly extending base flangeformed integral therewith and interposed between said support flange andsaid attachment flange in laminar adjacency thereto; and attachmentmeans securing said attachment flange to said support flange forclamping said backing member, said cover and said evaporator in firmassembly, whereby said cover base flange forms an insulative barrierbetween refrigerated portions of said evaporator and said backingmember.
 7. In an ice maker as defined in claim 6 and furthercharacterized by a plurality of concentric, radially spaced, dependingsealing ridges formed integrally on said cover base flange and sealinglyabutting an upwardly projecting surface of said support flange forforming a labyrinth seal between said cover and said evaporator.
 8. Inan ice maker, means forming an evaporator unit having an internal,refrigerated cylindrical surface forming an internal bore; an innercover member having a central passageway and a collection chamberreceiving ice flake product and directing the same to said passageway;and said cover having a central, circular, inverted cup-shaped bodyportion sized to extend across and close said evaporator bore; saidcover having an upstanding neck formed integral with said body portionand having an out-turned flange forming a laterally opening channel; anouter backing member having said cover nested therein and clamping saidcover to subjacent portions of an ice maker, said cover being composedof a thermally insulative material having a lower thermal conductivitythan that of material forming said outer backing member; said backingmember having an annular top wall overlying said cover body portion andhaving inner terminal ends received in said laterally opening channeland forming an aperture closely receiving said upstanding neck.
 9. In anice maker, means forming an evaporator unit having an internalrefrigerated cylindrical surface forming an internal bore; icecollection means comprising a cover member composed of a thermallyinsulative material and having a central passageway and a collectionchamber receiving an ice flake product from said evaporator anddirecting the product to said central passageway; said cover having acentral body portion sized and configured to extend across and close andend of said evaporator bore; said cover body portion having a pluralityof collection channels therein forming said collection chamber andextending from a periphery of said body portion and to said centralpassageway in a generally spiral path for mechanically transferring theice flake product received from the evaporator to said centralpassageway, with the thermally insulative material on the wall surfacesof said collection channels acting to enhance the mechanical transfer ofice product to said central passageway.
 10. In an ice maker as definedin claim 9 and further characterized by: said evaporator having aradially outwardly extending support flange formed at an upper endportion thereof; said cover having a base flange extending radiallyoutwardly of said body portion and formed integrally therewith, saidbase flange being disposed in laminar adjacency with said supportflange; and attachment means securing said base flange to said supportflange.